Conventionally, with an image forming apparatus such as an electrostatic type duplicating machine or a printer where a latent electrostatic image formed on a photoreceptor is developed into a toner image and then transferred onto a sheet, there has been provided a portable type image forming apparatus having a minimized size disclosed, for example, in Japanese Unexamined Patent Publication No. 2-171453.
An image forming apparatus of the above type comprises at the following least functional components:
an exposing means for forming a latent electrostatic image on a photosensitive means;
an image forming means for developing the latent electrostatic image formed on the photosensitive means into a toner image and transferring the toner image onto a sheet;
a sheet transfer means for transferring the sheet into an apparatus body and discharging the sheet through the image forming means, the sheet transfer means including a fixing means for fixing the toner image transferred on the sheet;
a drive means for driving the means; and
electrical equipments.
The above-mentioned functional components are, respectively, mounted on a reinforcing metal frame consisting of a pair of side plates, stay members connecting the side plates, and other parts which are disposed in a box-shaped resin casing.
In order to popularize the image forming apparatus having the above-mentioned construction for home or personal use, it is desirable that the apparatus should be made as compact and light as possible and the manufacturing cost and the selling price should be as inexpensive as possible. However, the conventional image forming apparatus necessitates the reinforcing frame for mounting thereon the above-mentioned functional components, so that the amount of components tends to increase. The above fact also results in the problems of incapable compact and light-weight designing as well as expensive manufacturing cost of the apparatus. Furthermore, this causes to require the superfluous process of mounting the reinforcing frame to the apparatus, which results in further increasing the manufacturing cost.
As compact and light-weight designing is promoted, the image forming apparatus can be made handy for any person, so that the possibility of applying an excessive impact onto the apparatus increases from hitting against an object or dropping the apparatus. When such an excessive impact is applied to the apparatus, it tends to receive damage such as crack formation or plastic deformation particularly at the connecting portions between the apparatus body and the reinforcing frame because of the difference in material and strength of them.
Although it would be possible to eliminate the reinforcing frame in view of the above problems, such arrangement from which the reinforcing frame would be eliminated would reduce rigidity of the apparatus body. Therefore, for the functional components, the application of external force to the apparatus would be a significant factor which would have never arisen in conventional constructions. Particularly an image forming apparatus having a compact and light-weight design is based on the concept of popularizing the apparatus for home or personal use, so that maintenance of the apparatus should be carried out not by the service personnel but by the user himself or herself. However, when any functional component of the apparatus malfunctions caused by the external force, it is virtually impossible for the user to cope with the malfunction by the user himself or herself owning to lack of technical knowledge which is required to understand that the cause of the malfunction lies in the manner of handling the apparatus. Taking the above-mentioned facts into consideration, it will be an inevitable and important factor to prevent the possible influence of an external force onto functional components in a portable type image forming apparatus.
Accordingly, the present invention is proposed in view of the above-mentioned conventional problems with the object to provide an image forming apparatus which necessitates no reinforcing frame to achieve compact and light-weight designing being capable of suppressing the possible influence of an external force onto the functional components of the apparatus.
It is another object of the present invention to provide an image forming apparatus being capable of reducing the manufacturing cost thereof.